CALL: FIT_MATHIESON


distance

  The distance between anode and cathode. The anode is assumed
  to be the place where the avalanches take place. The strip
  width is derived from the bin width of the input histogram.

  This parameter is mandatory, and should be entered in cm.

centre

  If the fit is successful, then this parameter contains on
  return the reconstructed track location in cm. The coordinate
  system is the same as the horizontal axis of the input
  histogram.

  This parameter should be modifiable and its value prior to
  the call is not used. Any matrix, histogram or string
  associated with it before the call is lost.

norm

  Contains on return, if the fit is successful, the normalisation
  of the fitted Mathieson distribution.

  This parameter should be modifiable and its value prior to
  the call is not used. Any matrix, histogram or string
  associated with it before the call is lost.

k3

  If the FITK3 option is specified, then this argument contains
  on return of a successful fit the K3 parameter that matches
  best the histogram. If a value is given on entry, then this
  value will be used as starting point for the fit. Otherwise,
  an initial value of 0.5 is taken.

  The argument must in this case be modifiable. Any matrix,
  histogram or string associated with it before the call is
  lost.

  If the NOFITK3 option is specified, then this argument must
  contain on entry your prefered value of K3. The argument is
  then not modified and the corresponding error is set to 0.

errors

  The errors returned are the square roots of the diagonal elements
  of the covariance matrix, multiplied by a correction factor equal
  to:

       sqrt(chi**2/(#points - #parameters))

  This correction factor is equal to 1 if the errors to the data
  points have been assigned correctly.

  These arguments must be modifiable, that is, they can neither be
  constants nor expressions.

options

  The options string may contain the keywords listed in the table
  below. The keywords should be separated by blanks or commas.
  Additional text may be added - no error message will be issued
  if unrecognised keywords are used.

  ---------------------------------------------------------------------
  Option     Meaning                                 Defaults
  ---------------------------------------------------------------------
  EQUAL      Assume equal weight of all points       Default
  FITK3      Fits the K3 parameter                   Default
  NOFITK3    Keep the K3 parameter fixed             Not default
  NOPLOT     Don't plot the histogram and fit        Default
  NOPRINT    Don't print details during the fit      Default
  PLOT       Plot the histogram with fit             Not default
  POISSON    Assume Poisson errors                   Not default
  PRINT      Print details during the fit            Not default
  ---------------------------------------------------------------------

Keyword index. Formatted on 10/11/98.